Digital electronic timepieces have in many cases been used as so-called functional electronic timepieces as represented by multi-functional timepieces having an alarm function, a chronograph function and similar functions, and electromagnetic wave-corrected timepieces that correct the time upon receiving standard electromagnetic waves, for the reason that digital electronic timepieces constituted by a digital circuit and a digital display device are adapted to processing and displaying the functional data.
Accompanying the recent trend toward developing analog electronic timepieces of the hand position storage type, however, analog electronic timepieces with hands are drawing much attention as multi-functional electronic timepieces.
The constitution of such an analog electronic timepiece has been described in detail in, for example, Japanese Examined Patent Publication (Kokoku) No. 61-38421.
The analog electronic timepiece disclosed therein is of the hand position storage type in which timing data for time is obtained by calculating and storing the time information by using a suitable timing counter and predetermined pulse signals (e.g., pulse signals that are generated one pulse a second) obtained by dividing the frequency of high-frequency signals generated by an oscillator to a suitable period, and the time same as that of the timing counter is displayed in an analog form by rotating the hands using a suitable pulse motor.
In an analog electronic timepiece of this type, the data stored in the timing counter and the data displayed by the hands must be in synchronism at all times. If these data go out of synchronism, a correction process must be carried out by manual operation to bring them back into synchronism.
However, the operation for bringing these into synchronism is so complex and cumbersome that general users find it very difficult to bring the data indicated by the hands and the data of the timing counter into perfect synchronism easily and within a short period of time.
The above-mentioned problem may not be so serious as long as the analog electronic timepiece simply displays the time. In a multi-functional electronic timepiece having special functions such as a function for displaying the passage of time, a stopwatch function, a global time function, a calendar function, etc., in combination, however, if the hands and the timing counter are out of synchronism this presents a problem in that the data for a particular function is not correctly displayed by the hands, and the above-mentioned functions are no longer useful.
In an analog electronic timepiece, the hands and the time data of the timing counter that had been brought in synchronism by a manual operation may become out of synchronism during use for a variety of reasons such as the infiltration of noise that changes the data of the timing counter, failure of the motor to turn despite a drive signal being applied thereto, for some reason, resulting in a delay of the hands. The main cause, however, results from a change in the voltage of the small cell that is used as a power source.
That is, as the voltage of the cell becomes lower than a predetermined value, the timing counter that operates using small amounts of energy continues to operate on a low voltage but the pulse motor that consumes large amounts of energy fails to rotate, i.e., failure to drive the hands results in a loss of synchronism. When the cell is replaced, the content of the timing counter becomes indefinite and synchronism is no longer maintained between the hands and the timing counter. After the cell is replaced, therefore, the crown and the push buttons must be manipulated many times to bring the hands and the data of the timing counter into synchronism with each other.
In the steps of producing analog electronic timepieces, furthermore, the hands must be initially set to be in synchronism requiring considerable precision.
In conventional analog electronic timepieces, therefore, a number of contrivances have heretofore been proposed to bring the hands and the timing counter into synchronism with each other.
Japanese Examined Patent Publication (Kokoku) No. 3-14150 discloses an electronic timepiece having a timing circuit and hands driven by a motor that is energized by the output of a motor drive circuit according to the content of the timing circuit, wherein when they are not in synchronism, the hands are quickly fed quick-feed signals from the motor drive circuit until the counter storing the positions of the hands becomes zero, the counter is held at zero, and the hands are stepped up to the zero position (twelve o'clock position on the dial) which is the same as the content of the counter by using an external switch while the counter is being held at zero.
Japanese Examined Patent Publication (Kokoku) No. 61-38421 discloses a system for keeping synchronism in which a switch is provided for each of the hands, e.g., for each of the hour hand, minute hand and second hand, the switches are turned on to generate pulses every time the hands pass through 0 o'clock, 0 minute, 0 second, and the counted values of the timing counter are reset by the above pulses. Furthermore, Japanese Examined Patent Publication (Kokoku) No. 3-454093 discloses a system in which when the memory of an electronic circuit is going to be lost by the replacement of the cell, the unchanging fixed data that should be preserved is initially stored in a nonvolatile memory and are then brought back to the electronic circuit again after the cell has been replaced.
The above-mentioned systems, however, involve problems. With the system disclosed in, for example, Japanese Examined Patent Publication (Kokoku)) No. 3-14150, a person carrying the timepiece must manipulate it when the cell is replaced, requiring a cumbersome operation for accomplishing correct synchronism, which cannot be accomplished with ease in a short period of time.
The system disclosed in Japanese Examined Patent Publication (Kokoku) No. 61-38421 has an advantage in that the timepiece can be brought into synchronism without requiring the person carrying it to effect the manipulation. This system, however, requires additional switching mechanisms that make the device complex and bulky, which goes against the modern trend toward decreasing the size and thickness, and is disadvantageous in terms of cost. Furthermore, the switches impair reliability depriving the timepiece of commercial value.
The system disclosed in Japanese Examined Patent Publication (Kokoku) No. 3-45409 is concerned with a digital electronic timepiece without hands, wherein the unchanging fixed data such as the data for adjusting the frequency is stored temporarily in a nonvolatile memory. This system cannot be used for storing the data in the nonvolatile memory under the condition where the content of the time counter that is constantly changing is maintained in synchronism with the positions of the hands, which is carried out by the present invention.
The object of the present invention is to provide a hand display-type electronic timepiece which is simply constructed, enables the manufacturer or the user of the analog electronic timepiece to easily and correctly accomplish synchronism between the hands and the timing counter, and does not require the operation for bringing the hands and the timing counter into synchronism when the cell is replaced by the user, eliminating the problems inherent in the aforementioned prior art.